Ozma puts the Weapons to shame in that he can decimate a level 99 party while you sit back and watch helplessly. The amount you can prepare before fighting him is somewhat limited. He's far too random to really give you the opportunity to employ any sort of strategy aside from trying to dish out six 9,999 damage attacks before he heals himself and/or kills you. In addition, his speed is incredible. Even with Auto-Haste equipped, I've suffered through three attacks in a row on his part before.

It's entirely possible to go into a fight against Ozma with a Level 60 party and finish him off after a few rounds while experiencing almost no opposition, but it's just as possible that he'll cast Meteor and wipe out your entire level 99 party before you can act.

There have been instances where I've duked it out with him for nine or ten rounds and died, only to be insta-killed by Meteor right away in my next attempt at beating him.